Instrumental manual activity is a hallmark of behavior in primates. It is an expression of cognitive as well as neuromotor and musculoskeletal function. Nonhuman primate models of such activity afford opportunities for intensive, controlled research not possible with human subjects and provide a comparative perspective that complements the work of developmental psychologists in this area. The five studies of this project focus on assessment of three aspects of instrumental manual activity in children and nonhuman primates: i) spatial competence in such tasks as planning and anticipating movement of the self, single objects, or objects with respect to each other; ii) coordination of bimanual activity, and iii) hierarchical organization of sequences of manual actions. Identical tasks will be presented to children at 11, 16, and 21 months of age, capuchin monkeys Cebus apella), and members of three ape species (bonobo, Pan paniscus; chimpanzee, Pan troglodytes; orangutan, Pongo pygmaeus). Tasks will be presented at the child's home or in the nonhuman subject's home cage or living area during several half-hour to hour-long sessions. Each subject will participate in spontaneous play with a variety of objects as well as in computer-mediated tasks in which joysticks, buttons or dials are used to control an image on a video monitor. Data from each study will be examined for within-group (i.e., monkey, ape, human) norms and between-group contrasts or similarities. The findings of all of the studies, considered jointly, will provide a broad picture of the relations among different aspects of instrumental manual activity in three primate families as well as of ontogenetic changes experienced by humans during their second year of life. It will also allow evaluation of the suitability of using these primate species as models of early instruments competence in humans.